Subterranean Jetting Tool

ABSTRACT

The present invention relates to a jetting tool and method useful for inserting coiled or stick tubing further into subterranean wells, to permit additional production capacity to be realized from the well. The tool is located near a distal end of the tubing and can be used to generate and insertion thrust that facilitates insertion of the tubing.

RELATED APPLICATIONS

This application claims benefit of and priority to U.S. provisionalapplication Ser. No. 61/359,978, filed Jun. 30, 2010, the entirecontents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to devices and methods for conveying atubing work string, such as coiled tubing or stick pipe further intoproduction or other subterranean wells, and in particular into lengthyand horizontal wells.

BACKGROUND

Subterranean wells, such as oil and gas production wells, can be verydeep and long extending, e.g., 12,000 feet underground. A productionzone in such a vertical well might be only a few hundred feet in lengthor vertical height.

Some production wells, e.g., wells in the Haynesville Shale area ofLouisiana, can be 8,000 to 12,000 feet deep followed by, e.g., 5,000 to10,000 feet of additional horizontal run.

When setting a well up for production, tubing is inserted into the well,and sometimes into a well casing. Coiled tubing is commonly used forthis purpose. A ported sub (also known as a ported nipple) is mounted atthe end of the tubing, through which fluid is pumped as the tubing isinserted into the well. As the tubing is inserted into the well thefluid is pumped into the tubing, travels to the ported sub, and isgenerally discharged from ports in the ported sub in a transversedirection, i.e., in a direction that is at a right angle to thelongitudinal axes of the tubing and/or the casing. The discharged fluidthen returns to the surface via the annular space between the outside ofthe tubing and the inside of the well or casing.

When coiled tubing is used, the coiled tubing (pipe) is unrolled from aspool. As long lengths of the tubing are inserted into the straight wellor casing, friction develops between the external walls of the tubingand the internal wall of the casing. This friction can cause the tubingto buckle as long lengths are inserted. Additionally, radial rotation ofthe tubing to eliminate or prevent the buckling is not practical sincein the case of coiled tubing the tubing is mounted on a supply spool,and rotating the spool for this purpose is not readily achievable.

Substantial friction is also developed as straight tubing (stick pipe)is inserted into long horizontal runs.

However, in many wells merely pumping the fluid down the tubing isinsufficient to prevent buckling of the tubing when the tubing runs arevery long, even when the fluid includes friction reducers, glass beads,and the like, in an attempt to free the tube. In such situations, whenthe tubing cannot be inserted sufficiently near the bottom or end of thecasing, lost production opportunities result as reserves near the farend of the casing cannot be produced by the well.

What is needed are devices and techniques to permit tubing, such ascoiled tubing, to be further inserted into the casing of lengthyproduction wells so additional reserves can be produced.

SUMMARY OF THE INVENTION

The present invention includes a jetting tool that can be mounted at adistal end (the far end, or lower end) of the tubing to further draw thetubing into the well. The jetting tool includes ports that have theirdischarge angled back towards the entrance of the well. The amount ofangle is chosen to maximize the amount of downward thrust generated bythe jetting tool, so it can assist with pulling the tubing further intothe casing. Preferably the jetting tool has between four and eight jets,each directed toward the well head. The amount of fluid being pumpeddown the tubing can be about 2 barrels (bbl) per minute, with adifferential pressure of about 400 to 500 psi (e.g., as measured at thesurface). This amount can be varied to change the amount of insertionthrust provided. For example, flow rates up to about 10 bbl/minute canbe used. This flow provides thrust that helps pull the tubing straight,assists in overcoming frictional force between the tubing and thecasing, and helps move the tubing further into the well.

One aspect of the invention features a jetting tool for inserting atubing work string into a subterranean well, such as a hydrocarbonproduction well. The jetting tool is sized for insertion into the welland has a generally cylindrical body. The body has a proximal and adistal end, the distal end of the tool for insertion into thesubterranean well, followed by the proximal end. The proximal end isconfigured to be attached to a tubing work string, such as coiled tubingor stick tubing.

The jetting sub can have an interior supply channel within the body thatis configured to receive a flow, e.g., from the tubing work string. Itcan also have a plurality of jets located at an exterior surface of thebody, the jets being configured to receive the flow from the interiorchannel and angled to impart an insertion thrust to the tubing workstring. The discharge flow from the jets creates the insertion thrust.

The jets of the jetting tool can have a discharge angle J of betweenabout 15 and 35 degrees, and there can be between about 4 and about 8discharge jets on the jetting tool.

The outer body of the jetting tool can have an outer diameter of betweenabout 2 and about 4 inches. An inside diameter of the jets can bebetween about ⅛ and ½ inch, or about ⅜ of an inch. It can have betweenabout 4 and 8 jets, and they can be configured in one row, or more thanone row (e.g., two rows having four jets each). An embodiment has onerow of six jets, having and inside diameter of ⅜ of an inch. The distalend of the jetting tool can be attached to a perforating gun, and theproximal end can be attached to a tubing work string, e.g., thatprovides the flow to the jetting tool.

The invention also includes a method of inserting a tubing work stringinto a subterranean well through a surface well control head, such as awell head or a blow out preventer (BOP). The method facilitatesinsertion of a tubing work string into a subterranean well. It includesthe steps of positioning a jetting tool near a distal end of a tubingwork string, inserting the tubing work string through a surface wellcontrol head of the subterranean well (such as a BOP), and establishinga flow through the tubing into an interior of the jetting tool, suchthat the flow discharges the exterior of the jetting tool through aplurality of jets in the jetting tool.

A discharge flow from the plurality of jets of the jetting tool isdirected towards the surface well control head, thereby producing aninsertion thrust that further advances the tubing work string into thesubterranean well. The flow can be about 3 barrels/minute, whichestablishes a thrust of about 4800 lb/square foot. The flow can be fromabout 0.5 to 5 barrels per minute, or more, depending upon the needs ofthe well and the design parameters of the jetting tool (such as size andnumber of jets). A discharge velocity of the flow can be between about20 to 60 feet per second, or more, depending upon the design conditionschosen for the well. It is possible to use more than one jetting toolfor a well application, and the jetting tool can be machined from acombination of parts that are subsequently assembled.

Use of this method can overcome sufficient frictional resistance toenable at least an additional 5 to 15% of additional tubing work stringlength to be inserted into the subterranean well.

Another aspect of the invention includes a ported nipple for anin-ground production well, the ported nipple configured to be mounted ata distal end of a tubing work string, and including discharge jets. Theimprovement of the ported nipple includes angling the discharge jets atan angle of between 15 and 35 degrees toward a surface well control headof the production well, such that a flow exiting the discharge jetsimparts an insertion thrust to the tubing work string.

SUMMARY OF THE FIGURE

The foregoing discussion will be understood more readily from thefollowing detailed description of the invention, when taken inconjunction with the accompanying drawings.

FIG. 1 is a cross-sectional view of a subterranean well.

FIG. 2 shows a demonstration of fluid being discharged through the portsof a jetting tool.

FIG. 3 is a close-up view of a jetting tool according to an embodimentof the invention.

FIG. 4 is a cross-sectional view of an embodiment of the jetting tool.

FIG. 5 shows an end view of an embodiment of a jetting tool, whichdepicts a thread connection for mating directly with coiled tubing,without the need of a crossover (adapter).

DETAILED DESCRIPTION

FIG. 1 is a cross-sectional view of a subterranean well. As explained inExample 1 below, such wells can be 12,000 feet deep and have ahorizontal run of 5,000 feet. A perforating gun 105 can be near the endof the tubing work string, attached to a jetting tool 100.

FIG. 2 shows a demonstration of fluid being discharged through the portsof a jetting tool 100. Depicted at a distal end of the jetting tool 100is a perforating gun 105. In some embodiments the perforating gun isreplaced with a plug, such as a bull plug (not shown). An insertionthrust 125 is provided by a flow of fluid from a tubing working string(not shown), that supplies the flow to a proximal end of the jettingtool.

FIG. 3 is a close-up view of a jetting tool 100 according to anembodiment of the invention. The jetting tool can have a generallycylindrical body 200 with an OD, e.g., of 2″ to 3″ (nominal). Thejetting tool at the proximal end P is connected to the tubing, and canbe machined to have threads that correspond with and mate to the threadsof the tubing, such as a 2⅜″ PAC thread box. The other, distal end D ofthe jetting tool can have a common bull plug thread such that it can beconnected directly to a perforating gun 105. Alternatively, the secondend of the jetting tool can be threaded, e.g., having a 2⅜″ 8rd (8round) thread pin.

The jets 225 in the jetting tool can have machined ports that extendinwardly toward the ID of the tool at the pin connector end. These portsare steeply angled at an angle J (e.g., 15 to 35 degrees from thelongitudinal axis 250 of the jetting tool) toward the proximal end P tomaximize downward thrust imparted to the tubing work string. More thanone row of jets can be included about the circumference of the body,although only one row is depicted.

The tubing can be, e.g., 1.25 to 2⅜″. A perforating gun mounted belowthe jetting tool can have a diameter, e.g., of 2.125 to 3.375″, sosubstantial friction can also be developed between the outside surfaceof the gun and the inside surface of the casing.

FIG. 4 is a cross-sectional view of an embodiment of the jetting tool ofFIG. 3. A plurality of jets 225 (only one is shown) can receive a flowfrom an interior flow channel 350. The flow is then discharged throughthe plurality of jets at an angle J, thereby creating a downwardinsertion force due to the insertion thrust that is generated by thedischarge flow.

FIG. 5 shows an end view of an embodiment of a jetting tool, whichdepicts a thread connection 305 for mating directly with coiled tubing,without the need of a crossover (adapter). An interior flow channel 350is depicted, through which a flow can enter the jetting tool at theproximal end P, before discharge of the flow through the jets 225towards the proximal end P of the jetting tool. As shown, a bracket 360supports the jetting sub at a distal end D of the jetting sub, beforeinsertion into a well.

Example 1

When running TCP (tubing conveyed perforation) guns on coiled tubing, orregular tubing (stick pipe) in long horizontal runs, large amounts offriction are created as the tubing is used to push the tools toward thebottom of the well. This friction causes the tubing to buckle and “stackout,” such that additional tubing cannot be inserted into the well.

During the process fluid is constantly pumped down the tubing andcirculates back to the surface on the outside of the tubing. This energyis available and can be used advantageously. This concept was tested inNovember, 2009 on a natural gas production well in the Haynesville Shalefield in Louisiana. The well had been drilled to about 12,000 feet truevertical depth, followed by a horizontal run of an additional about5,000 feet. The horizontal run is used to produce additional gas in thesection, as it approaches the boundary of the next section (of land).

A producing section in wells in this field can vary from about 300 to800 feet of casing length. Thus, after perforation is complete, thehorizontal portion of the well can have the production capability of 10to 20 vertical wells.

For the test on this particular production well, the tubing could notinserted beyond a length of 16,000 feet due to buckling/friction of thetubing work string within the casing. Another 550 feet of productionlength remained at the far end of the casing, into which the tubingcould not be inserted. When a jetting tool using the present inventionwas installed on the tubing (between the end of the tubing and theperforating guns) insertion of the tubing for the additional 550 feetwas achieved, representing a total insertion length of between 16,500and 17,000 feet. The extra 550 of tubing insertion represents theproduction capacity of an additional vertical production well,offsetting substantial additional drilling costs to permit production ofthis portion of the gas field.

Example 2

Testing has shown that for a jetting tool with six jets having jetinside diameters of ⅜ of an inch, a flow of 1 barrel per minutegenerates a thrust of about 670 lbs/square foot. Two barrels/mingenerates a thrust of about 2100 lb/square foot, and 3 barrels/mingenerates a thrust of about 4800 lb/square foot. In this embodiment, aflow of 1 bbl/min corresponds to a discharge velocity of about 20 feetper second from the jets. A flow of three bbl/min corresponds to adischarge flow of about 60 fps. These large insertion forces areresponsible for obtaining the types of results exemplified above.

The invention is useful for all types of subterranean wells, includingwells being drilled that do not have a casing installed, and for wellsfor producing non-hydrocarbon products, such as water or hot water.

While the invention has been particularly shown and described withreference to specific preferred embodiments, it should be understood bythose skilled in the art that various changes in form and detail may bemade wherein without departing from the spirit and scope of theinvention.

1. A jetting tool for inserting a tubing work string into a subterraneanwell, the jetting tool sized for insertion into the subterranean welland comprising: a generally cylindrical body having a proximal and adistal end, the distal end of the jetting tool for insertion into thesubterranean well, the proximal end configured for attachment to thetubing work string; an interior supply channel within the body, theinterior supply channel configured to receive a flow from the tubingwork string; and a plurality of jets disposed at an exterior surface ofthe generally cylindrical body, the jets configured to receive the flowfrom the interior channel of the jetting tool, the plurality of jetsangled to impart an insertion thrust to the tubing work string in thedistal direction when a flow from the interior channel of the jettingtool exits the plurality of jets in a direction toward the tubing workstring.
 2. The jetting tool of claim 1 wherein the jets have a dischargeangle of between about 15 and 35 degrees.
 3. The jetting tool of claim 1wherein the plurality of jets consists of between about 4 and about 8jets.
 4. The jetting tool of claim 1 wherein an outer diameter of thebody of the jetting tool is nominally between about 2 and about 4inches.
 5. The jetting tool of claim 5 wherein the inside diameter ofthe jets is between about ⅛ and ½ inch.
 6. The jetting tool of claim 1wherein the jets have an inside diameter of not more than about ⅜ of aninch.
 7. The jetting tool of claim 1 wherein the distal end of thejetting tool is configured for attachment to a perforating gun.
 8. Thejetting tool of claim 1 wherein the jets are arranged in two rows. 9.The jetting tool of claim 8 wherein each row has four jets.
 10. A methodof facilitating the insertion of a tubing work string into asubterranean well, the method including the steps of: positioning ajetting tool at or near a distal end of the tubing work string;inserting the distal end of the tubing work string through a surfacewell control head of the subterranean well; establishing a flow throughthe tubing work string into an interior of the jetting tool, such thatthe flow discharges the exterior of the jetting tool through a pluralityof jets in the jetting tool; directing the discharge flow from theplurality of jets of the jetting tool towards the surface well controlhead, thereby producing an insertion thrust that further advances thetubing work string into the subterranean well.
 11. The method of claim10 wherein a flow of about 3 barrels/minute of flow establishes a thrustof about 4800 lb/square foot.
 12. The method of claim 11 wherein theflow is between about 0.5 and 5 barrels per minute.
 13. The method ofclaim 10 wherein a discharge velocity of the flow is between about 20and 60 feet per second.
 14. The method of claim 10 wherein a dischargevelocity of the flow is at least about 60 feet per second.
 15. Themethod of claim 10 wherein use of the jetting tool overcomes sufficientfrictional resistance to enable at least an additional 5 to 15% ofadditional tubing work string length to be inserted into thesubterranean well.
 16. A ported nipple for an in-ground production well,the ported nipple configured to be mounted at a distal end of a tubingwork string, the ported nipple including discharge jets, the improvementcomprising: angling the discharge jets at an angle of between 15 and 35degrees toward a surface well control head of the production well, suchthat a flow exiting the discharge jets imparts an insertion thrust tothe tubing work string.